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HOW TO MAKE 

CONVERTER 
STEEL CASTINGS 



By Arthur Simonson 



A comprehensive discussion of the methods 
involved in the manufacture of steel castings 
by the converter process. 

This work is compiled from a series of articles 
by the author, written for and published by 
The Foundry. 



Cleveland., Ohio, U . S. A. 

The Penton Publishing Co., Publishers 

1914 

SECOND EDITION 



.56 



Copyright, 1914 

THE PENTON PUBLISHING CO 

CLEVELAND, OHIO 



FEB 13 1914 



CONTENTS 

Page 

Chapter I 1 

Construction of the Converter 

Arrangement of the Converter and Cupohi 

Converter Operating Station 

Special Cupola for Melting the Iron 

Heating the Ladles 

Sand Grinding and Mixing for Steel Foundry Work 

Chapter II 12 

Lining the Converter 

Kind of Brick Used 

Life of the Lining 

Construction of Wood Forms L'sed for Lining the Converter 

Chapter III 18 

Analysis of the Iron to be Converted into Steel 

Calculation of the Cupola Charge 

Graphic Method of Figuring the Cupola Charge 

Chapter IV 22 

Operation of the Converter 

Blowing the Steel 

How to Overcome Difficulties During the Blow 

Analysis of Converter Castings 

Chapter V 29 

Hot Cracks in Steel Castings and How They May be Overcome 

Chapter VI 32 

The Steel Foundry Laboratory 
Equipment and Necessary Determinations 

Index 38 



111 



CHAPTER I. 

Construction of the Converter — Arrangement of the Converter 

AND Cupola — Converter Operating Station — Special Cupola 

FOR Melting the Iron — Heating the Ladles — Sand 

Grinding and Mixing for Steel 

Foltndry Work. 



XT will Ije the author's ohject. in this and succeeding chapters, to give 
a general idea of the science and art of making steel castings in a 
foundry equipped with the Tropenas system of steel-making. It is 
a mistake to think that the company operating a small converter 
plant can successfully compete in all lines of the casting business. There 
are, undoubtedly, branches where it cannot compete with the open-hearth 
and the malleable iron foundry. There are few things so light that they 
cannot be cast from the excessively hot steel made in the small converter, 
but for these tiny pieces, gray iron, malleable iron or brass are generally 
strong enough. On the other hand, for the very large pieces, say over 8 
tons in weight, the open-hearth is probably cheaper, in America at any rate, 
though in England a plant operating five converters is successful in com- 
petition with the open-hearth and produces over 600 tons per month of mis- 
cellaneous castings of all analyses, and varying from less than a pound up 
to 10 tons. 

The field of the small converter is ideally in the small and medium 
castings, and those calling for a specially high-grade material. It is an 
undisputed fact, that a well-handled converter of the Tropenas type pro- 
duces a superior quality of steel, sounder, closer-grained and stronger than 
can be otherwise obtained. In automobile work, motor boats for gears, 
valves and levers, turbine work, gas engines and general machine work, 
converter castings are particularly desirable. 

The realization of what can be done in the way of making light and 
intricate castings has led to the elaboration of engine and machine details 
in a remarkable way. A designer has no longer to take into consideration 
the possibility of not being able to get the castings he requires in steel. The 
small converter has made it possible to develop tremendous power engines 
occupying small space, and as proposition after proposition is put before 



Hoiv to Make Conz'erter Steel Castings 



the founder and solved, he is beginning now to reaHze the possibilities of the 
process. The increasing number of plants being erected and the success 
with which they are meeting, testifies to the realization of the claims made 
for the side blow converter since its inception. 

It is worthy of note that the open-hearth steel founders are now be- 
ginning to realize the usefulness of a small converter as an annex to their 
large furnaces, in this way being able to take care of absolutely any busi- 
ness that comes along, and thereby relieve the large furnaces of the tedi- 
ous, costly necessity of making the small castings. There is today also at 
least one case of a malleable iron foundry installing a Tropenas converter. 
It seems probable that the time is near at hand when every open-hearth 
furnace operating on castings will have as an adjunct one or more con- 
verters, the idea would then, be to make all the small castings with the con- 
verter and just enough of the larger ones to fill-in up to capacity. In dull 
times the entire output might be economically made with the converter. 

We will now describe in detail a plant consisting of one two-ton con- 
verter and having a capacity of about 40 tons of castings per week. It con- 
sists of converter, converter blower and motor, pulpit or operating station, 
cupola, cupola platform and elevator, cupola blower and motor, ladles and 
ladle heating plant, sand grinder and mixer. 

An analytical laboratory is also indispensable, and this has been made 
the subject of a special chapter. As for the foundry equipment, including 
cranes, flasks and miscellaneous rigging, it is the same for all foundries, 
no matter what process is used, but it may be well to make a few remarks 
on this subject in passing. 

Electric traveling cranes are now almost exclusively used with wall 
or jib cranes as accessories. All foundry buildings are, or should be of 
steel construction with ample lighting facilities. Up-to-date plants are pro- 
vided with heating and ventilating systems so that in summer, air from out- 
side can be distributed through the building, and in winter it is passed 
through steam coils. The heating of foundries is a very important mat- 
ter. If the sand is allowed to freeze it will cause endless trouble, particu- 
larly if green sand castings are made. The artificial lighting of a foundry 
for night work is a problem requiring considerable attention. The atmos- 
phere in a foundry is often smoky and always very dusty, and it requires 
a very good distribution of powerful lights to enable the men to work 
when necessary, at night as well as in the day time. The ovens for drying 
molds should be as large as possible, and their trucks designed of such type 
that the heating of axles and bearings will not affect their operation. 
Flasks, chains and general tackle should be as heavy as is convenient to 
handle. The less risk taken the better — and the foundry business has 
enough of them under the most favorable conditions. 

The writer is of the opinion that any amount of money judiciously ex- 
pended on the special tackle and rigging in the foundry pays a good dividend 
in safety, speed and economy. 



Hoiv to Make Con-c'crter Steel Castings 



The Converter. 

The converter is of 2 tons capacity, that is to say, it is capable of turn- 
ing out at each operation approximately 2 tons of steel. In this chapter 
it will be considered as a machine only ; its metallurgical side will be dealt 
with in a succeeding chapter. The illustrations, Figs. 1, 2, 3 and 4, will 
give a good idea of the general appearance of the converter. Fig. 1 shows 
the arrangement of the steel converter and the cupola ; Fig. 2 shows the 




Fig. 1 — Arrangement of Steel Converter and Cupcjla. The Metal 
From the Cupola is Conveyed to the Converter by a Jib Crane 



converter tilted while the metal is being poured into the vessel for the blow ; 
Fig. 3 shows the converter in operation and Fig. 4 shows the converter 
tilted to empty the slag after the metal has all been poured out. 



Hotv to Make Converter Steel Castings 



The shell of the converter is 5 feet in diameter and is made of ^ inch 
steel plates, perforated with .)/:^-inch holes spaced 8 inches center to center 
to allow the steam to escape when drying the lining. The amount of floor 
space occupied by the converter is about 16 feet square and the head room 




Fro. 2 — Pouring the Metal Into the Converter. 

required is al)out 18 to 20 feet to enable the whole of the flame, which 
comes out of the mouth, and which constitutes the means for judging the 
condition of the steel, to be seen at all times. 



How to Make Converter Steel Castings 



The converter is supported on steel trunnions, one of which is hollow 
and forms a duct for the air, connecting with the blast box at the back of 
the converter. This enables the air to be kept on continuously while the 
position of the converter is being changed. The blast box is double, and air 
can be admitted to either side separately, or in varying proportions. This 
is partly shown in Fig. 6, which is a section of the converter, both vertical 




Fig. 3 — The Converter in Operation 



and horizontal, showing the arrangement of the tuyeres, the level of the 
bath and the approximate position of the vessel while the blow is being 
made. The other trunnion is extended and carries a worm wheel which, 
through suitable gearing, is connected to a 4 horsepower motor. A hand 
wheel is also provided for making small movements of the vessel as required 



Hozv to Make Converter Steel Castings 



from time to time. The electric motor has been generally adopted for tilt- 
ing the converter, although any means may be employed, and plants are 
in operation in various places using compressed air, steam and hydraulic 
power. This is a mere detail and de])ends on circumstances. The 
converter is firmly bolted to pedestals, which are sufficiently high to allow 
the converter to make a complete revolution if necessary. This is advisable 
for facility in emptying the converter, and also to enable the whole of the 
metal to be poured out before the vessel is too low for the men to hold the 
ladles. 

The covers of the blast boxes are fastened on by means of keys, for 
quick removal to clean out a tuyere or to set the converter at the commence- 
ment of a blow. The upper box is fitted with a pipe having an independ- 
ent valve so that it may be shut off entirely if desired, or any required 
amount of blast admitted according to the conditions that arise as the 
blow proceeds. The lining of the converter will be dealt with in the next 
chapter. 

Converter Blower and Motor. 

The blower is of the positive pressure type, and must be capable of 
maintaining a constant pressure up to 4 pounds per square inch through 
the area of both sets of tuyeres, which consist of seven in the lower row, 
\}i inches in diameter, and seven in the upper row about l>4x->^ inches. 
A water-jacketed blower running at about 400 revolutions per minute, is 
commonly used and is satisfactory. Blast may be supplied by a blowing 
engine, but is not so satisfactory, as the pulsations of the engine, unless 
absorbed by a very large receiver, are manifest in the flame and interfere 
with the observation of the reactions. A rotary blower is best on this ac- 
count as it gives a practically constant stream of air, and makes the flame 
perfectly steady, at least as far as outside influences are concerned. The 
blower should be direct-connected to a motor of about 73 horsepower ; no 
less is advisable, as it is better to have a little power in reserve and not run 
the risk of the circuit breaker flying out all the time, for when this happens, 
it always seems to occur at a critical time in the blow and may lead to 
clogging of the tuyeres, loss of time and possibly disaster to the blow. The 
blower should be placed close to the converter, but not too close, as a fair 
length of the 12-inch air main serves as a reservoir and gives elasticity to 
the blast. Elbows in the pipe should always be avoided. 



Operating Station. 

This is the place where the operator stands to watch the progress of 
the blow and to tilt the converter according to the different requirements of 
charging, pouring, etc. It is better to place this at one side of the vessel,. 



Ho-iV to Make Converter Steel Castings 



about 20 feet away, if possible, so that the heat will not inconvenience the 
operator and that he may see the whole of the flame. It is not advisable 
to place the pulpit across the building as in this case the flame is fore- 
shortened, and it is not possible to see the smoke, sparks, etc.. so clearly. 
The pulpit contains the controller for tilting the motor, the lever of the by- 
pass valve to regulate the pressure of air going into the converter, a signal 
whistle to the blower room to signal the engineer when to start and stop 
the blower, and a mercury pressure gage. The engineer, on receiving the 
signal of two short blasts, starts the blower at full speed and maintains it 
at this speed all through the blow. Variations of pressure are then obtained 
by the operator opening or closing the by-pass and allowing more or less 
air to escape through a pi])e leading to the outside. The blast gage, read- 




FiG. 4 — Converter Tilted to Empty 

THE Slag After the Metal 

Has Been Poured Out 



Fig. 5 — The Converter Operat- 
ing Station 



ing in pounds, is attached to the blast main between the blower and the 
by-pass. Fig. 5 gives a view of the pulpit ; A is the lever of the by-pass 
valve ; B is the controller of the tilting motor ; C is the whistle, and D is 
the mercury gage. 

Cupola. 



There has been a great deal of discussion as to the best type of cupola 
for the Tropenas converter. It is largely a matter of opinion. The fact 



Hoiv to Make Comrrter Steel Castin 



Qs 



is, that it is required to melt about 5 tons per hour of a charge consisting 
oftentimes of as much as 50 per cent of steel scrap, to melt it hot, and to 
be capable of running very long heats, sometimes as long as eight or nine 
hours. Any cupola that will meet these conditions is suitable. It must 





Fig. 6 — Vertical and Horizontal Fig. 7 — Special Cupola for Melt- 
Sections OF vSteel Converter. ing Iron for the Converter 

be remembered that in melting low phosphorus stock such as is used in 
steel-making, a hot melting cupola is necessary, and facilities must be pro- 
vided for taking care of a large quantity of slag, as considerable flux is used 
to keep the sulphur as low as possible. There has also been considerable 



Hozv to Make Converter Steel Castings 




Fig. 



8 — Heating a Large Ladle 
With an Oil Burner 



discussion as to the desirability of having a cupola large enough to melt 
the total charge for one blow at one tap, or getting it at two taps. After 
long experience, the author has come to the conclusion that a somewhat 
special cupola is the best, and this after using almost every kind that could 

be mentioned. The writer's idea of a 
suitable cupola is one built on the 
lines of a blast furnace, with a bustle 
pipe and pendant tuyeres, such as is 
illustrated in Fig. 7. The bustle pipe 
or blast box must be ample in size in 
order to maintain equal pressure at all 
of the six tuyeres. The advantage of 
this type of cupola is that the tuyeres 
are always clean, and if any slag or 
iron runs into them it runs out again 
without going into the blast box. 

The cupola should be about 54 
inches in diameter, lined with two 
rows of 4j^-inch bricks, giving an in- 
side diameter of 36 inches. The tuy- 
eres should then be placed so that the 
slag hole, which is 6 inches lower than 
this, will be sufficiently high to allow 
of the required amount of iron being 
tapped out when it has melted up to 
this height. In this way the cupola 
will be kept entirely free from slag, 
the tapping spout will be kept clear 
through a long heat, and there will be 
little risk of scaffolding. A blast 
pressure of from 10 to 14 inches of 
water should be maintained. 



Cupola Platform and Elevator 

The cupola platform should be 
higher than is usual in iron foundries, 
as it should be arranged to take care 
of a height of not less than 13 feet of 
cupola from bottom plate to charging 
door. The platform should be strong 
enough to carry a day's run of melting stock, and should be figured to carry 
not less than 500 pounds per square foot. It should be roomy, and pro- 




FiG. 9 — Method of Heating Hand 
Ladles 



vided with facilities for good ventilation as a good deal of smoke from the 



Hoiv to Make Comrrtcr Steel Castings 



converter finds its way up there and at times it is a Aery undesirable place 
to work. The elevator, preferably electric, should have a large platform 
and should be capable of lifting about 3 tons at a time at a speed of about 
60 feet per minute. 

Cupola Blower and Motor. 

Any of the accepted types of cupola blowers are satisfactory, whether 
fan or pressure blower, but they should be designed to give ample volume, 
on account of the high tuyeres and the large percentage of steel scrap used 
in the charges. The motor is of about 25 horsepower. 



Ladles. 

The Tropenas converter makes 
such exceedingly hot steel that it 
can all be poured over the lip of 
the ladle, bottom-pour ladles not 
being necessary. For pouring small 
work such as is made in snap molds, 
hand or bull ladles holding about 
150 pounds, are commonly used. 
They are about 13 inches in diame- 
ter at the top and are lined to a 
thickness of ly^ inches. The 
shanks are about 7 feet long, and 
have one double end for the man 




Fig. 10 — Oil Burner for Heating 
Ladles 




Fig. 11 — Roller T^pe Grinder for 
Grinding and Mixing the 
Molding Sand 



Fig. 12. — Type of Grinder 
ferred by the Author 



Pre- 



who is to do the pouring and a single end for the helper. The crane ladles 
are the same as iron foundry ladles, except that they are generally a little 
smaller in diameter in proportion to their height, to reduce the loss of heat 
by radiation. They are preferably geared with pin spur gearing instead of 



10 



Hoiv to Make Converter Steel Castings 



worm and wheel, as this gives a greater control, steadier liow and less 
possibility of a drop of the ladle when the gearing is worn. 

Ladle Heating Furnace. 

Ladles are generally heated to redness before filling with steel. In the 
case of the large ladles, this is done either by inverting them over an oil- 
burning furnace, or introducing an oil burner through a portable cover 
placed over the top of the ladle. The latter is illu.strated in Fig. 8. 

A device for heating small ladles, arranged by the author, is shown in 
Fig. 9. It consists of a series of small oil burners placed side by side, 
spaced about 18 inches apart from center to center, and a vertical plate with 
a two-inch hole opposite each burner, through which the flame passes and 
fills the bull ladle, which is reared against the plate. In this way any number 
of ladles can be heated, according to the length of the plate, or, if required, 
one ladle can be heated white hot in 10 minutes. It takes up very little 
floor space, is clean and easy to operate. Fig. 10 is a detail of the burner. 

Sand Grinder and Mixer. 

A grinder of the roller type is generally used. The usual type of mixer 
is illustrated in Fig. 11, but the author prefers the type shown in Fig. 12. 
In this mixer, while a perfect mixture of the sand is obtained, there is not 
so much crushing of the grains, and the resulting sand is more open, as is 
desirable in steel molding. This mixer is also very speedy in mixing sand, 
making it "strong" in much less time than the heavy roller grinder. 



11 



CHAPTER II 

Lining the Converter- — Kind of Brick Used — Life of the Lining — 

Construction of Wood Forms Used for Lining 

the Converter 

XN attempting to give a detailed description of the operation of a 
Tropenas plant, it is realized that no amount of written instruction 
will enable one not thoroughly acquainted with steel-making in 
general, to produce any kind of castings, to say nothing of the high 
grade of work that is called for today. The only way to learn how to 
operate a converter plant is to spend a long time in company with one who 
has had considerable experience and is perfectly familiar with the reactions 
that take place. It is true that when the converter was first introduced the 
pioneers had no one to instruct them, but it would be much too costly for 
all to learn by the same method. It is true, indeed, that after being under 
personal instruction and seeing a great many blows made, conditions may 
arise, after the operator is left to himself, which may puzzle him, and 
cause him to forget some of the principles that have been drilled into him. 
It is only by the strictest attention to details that success is achieved, but 
this is true of all trades, not only steel-making. An unsuccessful foundry 
business resembles a Kansas cyclone in its certainty of disaster — quick and 
complete. A foundry that is not watched at every point can absorb money 
as fast as Rockefeller can pour it in, as many a poor man has discovered. 
The essentials to success are shrewdness, watchfulnes and science. 

Lining of the Converter. 

There are two or three ways to line the converter, and they are all 
equally good, the factors determining the use of any one being convenience 
and local conditions. It may be lined with special blocks, which, while 
expensive, make the time occupied in repairs much less, this being often a 
very serious matter when the converter needs repairing and orders are 
waiting fulfillment. The chief drawback to the use of special blocks is that 
in making repairs, a large amount of good brick has often to be cut away 
to make room for the new ones. A sand lining, rammed in to shape, may 
be used and is probably as good and cheap as any, provided the proper 

12 



Hoiv to Make Converter Steel Castings 



grade of material is available. The third way is to use the ordinary shapes 
of furnace brick. This is probably the most common way and will be de- 
scribed in full detail, as it probably calls for more explanation than the 
others. Whatever material is used, it is necessary that it should be as 
refractory as possible, and nothing should be used in the way of brick that 
has been burnt at a lower temperature than is necessary to turn over a 
3,500-degree Seger cone. This means about 95 per cent silica and almost 
absolutely free of lime and magnesia. In the case of the ganister mixture. 




Fig. 13 — Wood Form Used for Lining the Converter 



the very best quality of silica clay must be used and in order to cause it to 
set very hard, it may be mixed with weak lime water. 

Lining the Converter With Silica Brick. 

The bricks used are the square, 9 x 4>4 x 2^^ inches, with the arch 
9 X 4^ X 2>4 x 1>4 inches, the wedge, 9 x 4i/^ x 2^^ x 1^ inches, and a 
special wedge used in the mouth. 9 x 414 x 2^/2 x 1 inches. A small quantity 
of split brick is also required. This is a rectangular brick one-half the 
thickness of the ordinary square. 



13 



Hoiv to Make Converter Steel Castings 



Two or three rough wooden forms should be prepared, having dimen- 
sions as shown in Fig. 13. They are made by sawing out boards for top 
and bottom, 2 inches less in dimensions each way, and then nailing 1-inch 
strips on the edges. The forms are 18 inches high. Set the converter in 
a vertical position by means of a plumb line, and then commence the lining 
operations by laying ordinary firebrick in the circular bottom until a level 
of about 26 inches below the center of the lower tuyere slot in the bottom 
wind box is reached. Break all joints and set alternate courses at right 
angles. Use ordinary firebrick of good quality for this part of the oper- 




FiG. 14 — One of the Wood Forms Set 
IN THE Converter 

ation, as they are less friable than the silica brick, and do not come into 
direct contact with the heat. The cement used may be made of one-half 
each, high-grade silica clay and crushed silica rock. For grouting in the 
courses after laying, this cement may be thinned with water. 

The next step is to set one of the forms. The illustration. Fig. 14, 
shows the location of this. It will be seen that the circular part of the 
form is eccentric with the circular shell of the converter, and the part of 
larger radius, which gives the conformation of the face of the tuyeres, is 
set so that a line joining the ends of the arc is parallel to the center line 



14 



Hoiv to Make Converter Steel Castings 



of the trunnions. A course of arch hrick on end is laid around the form, 
and outside of this, a row of ordinary firebrick backing, and the remaining 
space between brick and shell is rammed-in with ganister. This procedure 
is continued until a level, 2^ inches below the center of the slot in the 
shell referred to is reached. 

This brings us to the most important point in the lining, namely the 
setting of the tuyeres. Upon this depends a great deal of the assurance 
of success in the subsequent manufacture of the steel, "the tuyeres, both 
individually and as a whole, must be set absolutely level, both m a direc- 
tion parallel to their length and also in a direction at right angles to this. 
In other words, the tuyeres must all be in exactly the same plane. Fig. 15 
shows the tuyeres grouped together and it will be noted that for con- 
venience, they are numbered No. in the center. No. 1 for the first tuyere 
on each side, then No. 2 and No. 3, respectively. The higher numbers 
diverge more from the center than the lower numbers, and the whole sys- 




2 . -^ 1 

Fig. 15 — Tuyere Block. 



tem is symmetrical. These tuyeres are made of the very highest grade of 
silica material available, and they are burnt at a very high temperature as 
they are subjected to the greatest amount of wear and tear and the greatest 
amount of chemical action. In setting the tuyeres, it must be borne in mind 
that the holes must be leveled and not the outside of the bricks, as the outside 
may be warped to some extent. 

Round iron bars, of smaller diameter than the tuyeres, should be in- 
serted in the holes and the leveling done on the protruding ends of these, 
this being the only w^ay that accuracy can be insured. Together with this 
leveling, care should be exercised that the tuyeres come opposite the slot 
in the shell communicating with the lower wind box to allow of an 



15 



How to Make Converter Steel Castings 



unrestricted passage of the air into the converter and the possibiHty of 
cleaning out any slag or iron that may inadvertently get into the tuyeres. 
After being satisfied that the lower tuyeres are correctly set in every par- 
ticular, the upper tuyeres are set directly on top of them. The upper wind 
box has a slot corresponding wnth the lower one, and the rectangular open- 
ings in these tuyeres should be in line with it. It is not necessary to use 
the same care in setting these tuyeres, as they are merely combustion 
tuyeres and do not at any time approach the surface of the iron. They 
are numbered similarly and have the . same conformation as the lower 
tuyeres. The body of the converter is then lined up to a point about 2 
feet below the top of the cylindrical part of the shell, at which point the 
wooden forms may be dispensed with. Be sure to leave no open spaces 
between the bricks, and grout all the joints well with thin grout. From 
this point a certain amount of mechanical skill is required in setting the 
brick, as it is largely a matter of hand and eye. It is not an easy matter to 
describe, nor is it an easy matter to accomplish, but the principle is to 
overlap each course from this point up the cone until the lining terminates 
at the mouth of the converter in a circular opening, 15 inches in diameter. 
The last two rows in the mouth may be made with the special wedge brick 
mentioned. After the lining is completed, the wooden forms may be burnt 
out. The bottom is then built-up with pure silica brick until a depth of 
from 16 to 17 inches below the bottom edge of the tuyeres is reached. 
This corresponds very closely to a capacity of 2 tons. The lining being 
now complete, a wood fire is started, the blast valve being shut-off and all 
covers have been removed from the wind boxes. If the blast valve from 
the blower is left open, it may happen that gas will accumulate in the pipe 
and cause an explosion, which may be more or less serious. In describing 
the lining of the converter, nothing has been said of the manhole door in 
front of the converter, which some operators use all the time an<i others 
have discarded. It is most useful in making repairs, enabling the con- 
verter to be cooled oft' very rapidly and also forms a convenient way of 
handing in to the bricklayer his supplies of bricks and cement. When this 
is used, an arch should be built around the opening in the shell and filled 
in afterwards ; then when the manhole is punched out, the remainder of the 
lining is undisturbed. 

Life of the Lining. 

It is almost impossible to give definite figures as to the life of 
furnace linings. So much depends on shop practice and quality of ma- 
terials, that it is impossible to make an accurate estimate. For instance, 
if a furnace is run every other day and repaired every other day, it will 
last longer than if run daily for the same number of blows. There is a 
limit to the amount of patching that can be done, and if it is done before 
it is too late, it will not be necessary to cut away a lot of good brick in 

16 



Hozv to Make Converter Steel Castings 



order to make extensive repairs. The inner row of brick, that is the silica 
part of the hning, should never be allowed to be entirely penetrated. By 
making repairs at as short intervals as possible and preserving the original 
lines of the furnace, the life of linings will be preserved indefinitely, and 
the blows will be nuich more regular and uniform. The parts that are 
most subject to corrosion are the regions immediately surrounding the 
tuyeres, and at the base of the upper cone where the metal lies when the 
converter is in the pouring position. When repairing the tuyeres, bars 
slightly less in diameter than the holes should be inserted and ganister 
rammed around them and allowed to dry with the bars in place. By care- 
ful attention to repairs as many as 150 and even 200 blows can be made in 
a converter before it is necessary to renew the tuyeres, and up to 1,000 
blows before it is necessary to entirely reline. A new set of tuyeres can 
be inserted in about three hours. A considerable amount of the depreci- 
ation of the lining is caused by crushing and spalling. Silica brick has 
a very high coefficient of expansion and the alternate heating and cooling 
of the lining causes it to crush at one time and spall off at another. The 
expansion is so great that the bolts holding down the upper cone some- 
times pull apart, the heads flying a considerable distance. After a converter 
has been newly lined, these bolts should be loosened to allow the expansion 
to take place. 



17 



CHAPTER III 

Analysis of the Iron to be Converted Into Steel — Calculation of 
THE Cupola Charge — Graphic Method of Figuring 
the Cupola Charge 

^^^^^^IIE metal that is put into the converter to be converted into steel 
m (r\ must be of a definite composition within certain limits. Before 
^^ J reaching the converter it has to be melted in a cupola, where certain 
^^^ losses take place. These losses have to be taken into consideration 
when figuring the charges. In specifications for steel castings a limit is gen- 
erally set for the content of sulphur and phosphorus, and as in no acid 
furnace can this percentage be reduced, it is necessary to provide raw 
material sufficiently low in these elements to meet the specifications. In 
this respect it is exactly the same as the open-hearth practice. The analysis 
of the metal before blowing must be : 

Per Cent 

Silicon 1.80-2.10 

Manganese 0.60-1.00 

Carbon about 3 

Sulphur and Phosphorus as low as possible 

The cupola charges are made up of pig iron and steel scrap. The steel 
scrap generally consists of the heads and runners, scrap and defective 
castings from previous heats. Outside scrap is so uncertain in its compo- 
sition that it is unsafe to use it. As a rule, the best way is to arrange 
to melt in the cupola just the amount of scrap made in average daily 
practice. If a surplus accumulates, the percentage can be temporarily in- 
creased, and if a shortage occurs, the amount can be cut down. Ordinarily, 
with a satisfactory operation of the plant, about 20 to 25 per cent of steel 
scrap can in this way be carried in the cupola charges. The flux used in 
the cupola consists of limestone or oyster shells, and the coke is 72-hour 
coke with sulphur, 0.75 per cent or thereabouts. 

Calculating the Cupola Charge. 

There are two ways in which this may be done, a graphic way and an 
arithmetical way. In figuring out the charge the two elements, which are 
closely controlled, are the silicon and manganese, and particularly the sili- 

18 



How to Make Converter Steel Castings 



con. This element is always figured first. As regards sulphur and phos- 
phorus, it is understood that they are as low as possihle in the raw mate- 
rials so that after that point has been settled, they may be neglected. Car- 
bon, that is, total carbon, is practically the same in all grades of pig iron 
used, and may be neglected on that account, as it will be practically uniform 
anyway. The relation of the combined carbon to the graphitic does not 
make any difiference, as after the first few minutes' blowing, it will all be in 
the combined state. 

The first thing to be decided is the amount of scrap it is proposed to 
carry in the charge. Of course there are cases where the grade of pig iron 
available will place a limit on the amount of scrap that may be used. If 
the pig iron is all high silicon, it will be imperative to use a high per- 
centage of scrap to cut down the silicon to the required amount. If the: 
pig iron is low in silicon, it may be possible to use only a very small pro- 
portion of scrap. But for the purposes of this example we will suppose that 
the conditions are ideal, that we have the correct kinds of pig iron and 
are able to carry any reasonable amount of scrap. As stated above, it is 
wise, all things being equal, to confine the scrap to that made in the plant, 
and in an ordinary way this will amount to say, from 20 to 25 per cent. 
Let us assume that we have two brands of iron analyzing : 

No. 1 No. 2 

Per Cent. Per Cent. 

Silicon 3.50 2.00 

Manganese 0.25 1.50 

Let us assume that our steel scrap averages silicon, 0.25 per cent and 
manganese, 0.75 per cent. Let us also assume that we will carry 25 per 
cent of scrap. 

Problem. 

In a 100-pound charge, what quantities of the above No. 1 and No. 
2 pig irons and steel scrap will give a mixture with an analysis of say, sili- 
con, 2.00 per cent, and manganese, 0.80 per cent? We know how much 
steel scrap we are going to carry and will figure the silicon first, as follows : 

(Weight of scrap X per cent silicon) + (weight of pig iron X per cent sili- 
con ) = (1,000 pounds mixture X 200 per cent silicon) 

(250 X 0.25) -^ (750 X X) = 2000 

62.5 + 7S0X = 2000 

X ^ 2.5833 

The next question is: In a charge of 750 pounds, how much pig iron. 
No. 1, 3.50 per cent silicon, and how much pig iron. No. 2, 2.00 per cent 
silicon, will give a mixture containing 2.5833 per cent silicon ? 

19 



Hoiv to Make Converter Steel Castiii 




PercerJ of ifjjjcoiy /o Cirpo/a^. 

iZ/eeJ ifcj-i^ CorJeJr\ii\.j 2s7 ifjjicon..- 



FiG. 16 — Graphic Method of Figuring Cupola Charges 

20 



Hozv to Make Converter Steel Castings 



Let X equal the weight of pig iron Xo. 1 containing 3.50 silicon, then (750 ■ — 
X) represents the weight of pig iron No. 2 containing 2.00 silicon, and (X X 
3.50) + (750 — X) 2.00 = (750 X 2.5833) 

3.50 + 1500 — 2X = 1937.5 
X = 291.6 

The quantity of No. 1 pig iron required is, therefore, accurately 291.6 
pounds, and of No. 2 is 458.4 pounds. In round figures, the amounts of 
our cupola charge of 1,000 pounds would therefore be: 

Pounds 

No. 1 pig iron 290 

No. 2 pig iron 460 

Steel scrap 250 

Let us check this over to see if it is correct : 

(290 X 3.5) + (460 X 2.00) + (250 X 0.25) = (1000 X 2.00) 
1015 + 920 + 62.5 = 1997.5 

This figures out as closely as it is possible to weigh pig iron. The 
above calculations cover the silicon only, and while they seem bulky, they 
have been put down in detail to make it perfectly plain. As a matter of 
fact, the calculations are made in a very few minutes. We must now see 
how these weights will result in content of manganese : 

290 pounds No. 1 X 0.25 manganese) + (460 pounds No. 2 X 1.50 manganese) 
-f- (250 pounds steel scrap X 0.75 manganese) -r= (1000 pounds total charge X X 
per cent manganese), that is: 

72.5 + 690 + 187.5 = 100 X 

X = 0.95 per cent 

Allowing for the loss of manganese that takes place in melting in a 
cupola, this 0.95 per cent will probably be a shade under 0.80 when melted. 
The above mixture is therefore satisfactory and will give correct results. 
There will be a slight loss of silicon in the cupola, but the result will be 
well within the working limits. The above calculations can be worked out 
for any grades of pig iron by substituting percentages. 

The Graphic Method. 

This method has been figured out on the above lines and reduced to a 
diagram. Fig. 16. For the diagram reproduced here the author is indebted 
to A. H. Jameson. It is figured for two grades of steel scrap, one contain- 
ing 0.25 per cent of silicon and represented by the full line, and one con- 
taining 0.33 per cent of silicon and represented by the broken line. 

The diagram may be used in a variety of ways. For instance, it may 
be used to give the amount of steel scrap that a certain pig iron will carry 
to give a desired per cent of silicon in the cupola. Knowing the per cent 
of silicon desired in the cupola, and the amount of scrap that is available, 
it will give the per cent of silicon the pig iron must contain. Given the 
per cent of silicon in the pig iron and the amount of scrap to be carried, 
it will give the resulting silicon in the cupola. 

21 



CHAPTER IV 

Operation of Converter — Blowing the Steel — How to Overcome 

Difficulties During the Blow — Analyses 

OF Converter Castings 

'^ ^.^ f A V I N G considered in the last chapter tlie calculations of the cupola 
^ ^ charge, we will now follow its course through the subsequent pro- 
I F cedure. In melting steel scrap along with pig iron in a cupola, 
'^ ^^ provision must be made for hot melting and a higher ratio than 1 of 
coke to 7 of iron can scarcely be looked for. Cupola metal containing 25 
per cent of steel scrap is liable to be sluggish, therefore i)lenty of coke 
must be used and an ample amount of blast. It is one of the most neces- 
sary things to insure good hot steel in the converter, that the cupola metal 
should be hot and clean. Some operators use a cupola of sufficient size to 
tap out the necessary 2 tons at one time, while others prefer a cupola 
holding only 1 ton at a time and make two taps per blow. This has its 
advantages, as the iron remaining a shorter time in contact with the bed 
of coke is less liable to absorb sulphur. 

During the time the cupola has been charged and the iron melted, the 
converter has been prepared to receive the first charge of iron. It is neces- 
sary to get it to a high heat for this purpose, in fact the hotter it is the 
better. There are different ways of doing this and perhaps the most satis- 
factory is to make a coke fire and blow it with about 1 pound pressure 
from the blower for about two or three hours. Half a ton of coke is 
necessary and the converter is alternately blown for 15 minutes and turned 
upside down with a plate fastened over the mouth to retain the coke, and 
all tuyere box covers removed. This is to heat the bottom, which is not 
reached by the blast. It is essential that the bottom of the converter should 
be particularly hot. An oil burner or natural gas may be used, and is 
found satisfactory. 

When the converter has been thoroughly heated the coke is dumped 
out into the ash pit and the unburnt portion recovered to be used in drying 
ladles, etc. The converter should be ready at exactly the same time as 
the iron is tapped out of the cupola. The iron is collected in a ladle and 
transferred to the converter, after which the latter is turned down until 
the iron just comes to the lip. It is then skimmed entirely free from slag 

22 



Hoiv to Make Com'crter Steel Castings 



and this should be done before commencing each subsequent h\o\\\ Tlie 
vessel is then turned up again and as it rises, the operator looks through 
the tuyeres from the back of the vessel and continues the rotation until tne 
convex edge of the molten metal just appears over the edge of the tuyere. 
This is the most important point in the manipulation. The metal must be 
"up", but not in the tuyeres, and what constitutes "up" is a matter that 
takes some time to learn. It is well to use smoked glasses, or get the eyes 
accustomed to the color of the metal by watching it while being tapped 
out, poured into the converter and skimmed, otherwise it is comparatively 
easy to be deceived. When sure that the metal is exactly "up", the posi- 
tion of the converter is carefully noted. 

For this purpose the writer uses an indicator, as illustrated in Fig. 17, 
which is simply a quadrant of sheet iron attached to the rotating gland on 



Dial Rotating 
th Converter 



nxed Pomler 




Fig. 17 — Indicator for Noting Posi- 
tion OF Converter 

the trunnion, and a fixed pointer. The indicator is graduated in degrees, 
both ways from the vertical. 

When the converter is in the correct position for blowing, that is for 
obtaining the best results, the indicator should show about 5 to 9 degrees 
back from the vertical, that is the tuyeres should be inclined towards the 
surface of the metal and the direction of the blast should be very slightly 
downward upon it. Too great an angle would create too great a disturb- 
ance of the bath, which the Tropenas process is designed to obviate. If 
the angle appears too great or too small, a bull ladle of iron should be 
taken out or added as the case may be. The height of the iron in the ladle 
may then be noted and thereafter the cupola tender should have no difficulty 
in tapping out the correct amount. 

After getting the proper amount of good, hot, clean iron in the con- 
verter, adjusting and noting the angle, the tuyere box covers are put on 



23 



Hoiv to Make Converter Steel Castings 



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24 



Hozv to Make Converter Steel Castings 



and fastened in position. Blast is then turned on by giving the customary 
signal of two short blasts on the whistle or bell communicating with the 
blower room, and the motor should be speeded to give 3 pounds on the 
mercury gage when the by-pass valve is entirely closed. A record of the 
exact time of starting the blow should be made. 



Blowing the Steel. 

At the beginning, sparks and smoke should come out of the mouth of 
the converter but very little flame. The sparks should be copious, large 
and scintillating, and light yellow in color, the smoke noticeable but not too 
voluminous, and not too dark brown in color. An experienced operator, 
by noting the appearance of the sparks and smoke, can tell during the first 
minute of the blow whether the silicon content is right, and if he is going 
to have a hot blow or if it will be necessary to doctor it up as it goes along. 
The sparks should all go up the chimney in parallel lines, not crossing or 
shooting out at different angles. In from three to five minutes the char- 
acter of the sparks should change and become non-scintillating, and at the 
same time a flame should appear at the mouth of the converter. This is 
the time to open the upper tuyeres slightly, as the carbon is commencing 
to burn and extra oxygen is needed to complete its combustion and reap 
the full benefit from the heat generated. At the same time, the position 
of the converter should be advanced from 2 to 3 degrees, to compensate 
for the shrinkage in bulk due to the elimination of the impurities. 

During the next four or five minutes the flame increases in bright- 
ness and volume until what is known as the "boil" occurs. The flame 
should be carefully watched and if there is a tendency to throw out any 
metal, the blast pressure should be reduced. In extreme cases it may be 
reduced to 1^ pounds, but this is as low as it is advisable to go. There 
will always be a certain amount of projection of slag, and this is imma- 
terial unless it interferes with the observation of the flame. 

Sloppy blows are indicative of incorrect composition of metal, bad 
position of converter or too much blast. After maintaining its top position 
for one or two minutes, the flame dies down somewhat, and remains in a 
quiet condition for some minutes. The upper tuyeres may now be fully 
opened. The flame then rises again, becomes particularly bright and 
clear, and finally dies down for the last time with the evolution of copious 
brown smoke. 

The blow should be turned down a few seconds before the brown 
smoke appears, as this smoke represents burning iron, which means waste 
of metal and ruination to the remainder. The operator throws over his 
controller, turning down the vessel into the horizontal position, and a second 
after signals one whistle to the engineer to stop the blower. At this stage 
there is in the converter a bath of practically pure iron at a temperature 

25 



Hoiv to Make Converter Steel Castings 



well over 3,000 degrees Fahr. Fig. 18 gives the approximate curves of 
elimination of the elements in a typical blow. In order to recarburize it 
to the desired point, a weighed final addition of ferro-manganese, ferro- 
silicon, silicon-spiegel, or what not, is introduced. This may be added 
melted, in which case a small cupola or crucible furnace may be used, or 
it may be thrown in cold in lumps at the mouth of the converter immedi- 
ately after turning down the blow, before the slag gets too hard. In this 
case the lumps must first be dipped in water so that the explosion of the 
vapor as they strike the hot slag will part it and allow the alloy to go en- 
tirely into the bath of metal. This latter method has been found by the 
author to be far the most useful and regular way of adding final addi- 
tions. A special shaped core for skimming back the slag is fixed in the 
mouth of the converter and the metal is then ready to be tapped into the 
ladle. 

How TO Overcome Difficulties in Blowing Steel. 

This is a description of a perfectly normal blow, which should take 
place in from 15 to 20 minutes. Unfortunately all blows are not normal, 
a great many conditions having to be harmonized to produce this result, 
some of which occasionally go wrong. Some of the difficulties that arise, 
with their cause and cure will be briefly touched upon. The flame should 
make its appearance at the mouth of the converter in from 3 to 5 minutes. 
If it comes in less time, it is a sign that the silicon content of the 
metal is too low and the probabilities are that the blow will not l)e as hot 
as desired, for the silicon is the fuel, and the chief source from which heat 
is derived. To olTset this, when the flame makes its appearance, the con- 
verter should be advanced not more than two degrees and about 100 pounds 
of ferro-silicon in pig form thrown into the mouth of the converter. This 
has an astonishing eft'ect and as it melts and gives up its silicon the blow 
becomes noticeably hotter. If the blow goes on for more than five minutes, 
at the same time the blast pressure remaining the same on the blast gage, it 
is a sign that the iron is either too high in silicon or it is too cold. If 
caused by too high silicon, there may not be very serious results except 
that the blow will certainly be very sloppy, the loss will be abnormally 
great, the blow will be longer and the resulting steel may be high in silicon 
on account of tlie fact that the carbon burns out before the silicon is en- 
tirely eliminated. If the latter is the case there is nothing to do but coax 
it along and dose it with silicon after the flame makes its appearance. 

A frequent trouble due to various causes is the corking of the tuyeres. 
Its signs are an increase of pressure in the blast gage without any increase 
in the speed of the motor ; a change in the directions of the sparks, some 
of which shoot out at right angles instead of all being parallel, and delay in 
the progress of the reactions. Stoppage of the tuyeres may cause serious 
troubles, such as cold blows, and violent reactions. The tuyeres are corked 

26 



Hozv to Make Converter. Steel Castings 



by the formation of nozzles of slag on their extremities which tend to 
lengthen the tuyeres and may have openings in many directions, dispersing 
the blast and possibly permitting only a small amount of it to react on the 
metal. They are caused by cold metal, not setting the position of the vessel 
correctly, and not skimming it clean from slag at the commencement. When 
this corking is noticed it generally occurs before the flame makes its ap- 
pearance, and the converter should be turned down, the blast shut off and 
the projections or nozzles knocked off with an iron bar. The blast is then 
started and the converter returned to its original position, when it will 
usually proceed all right. It may be necessary to repeat this procedure two 
or even three times. The result of corked tuyeres is almost invariably a 
sloppy blow if nothing worse. 



Analyses of Converter Castings. 

In regard to the amount of final addition to be used a good deal could 
of course be written, also as to the materials to be used. In the first place, 
let us take the ordinary grades of simple or carbon steel. The analysis to 
be aimed at varies principally with the use to which the castings are to be 
put, and secondly to a less extent with the shape and weight of the piece. 
Speaking from the first standpoint it may be said that the analysis for ordi- 
nary machine or engine castings on which a good deal of machining has 
to be done should be carbon 0.25 to 0.30 per cent, silicon 0.25 to 0.30 per 
cent, manganese 0.60 to 0.75 per cent, and sulphur and phosphorus as low 
as possible, under 0.05 per cent. 

For castings which will be subject to a greater amount of wear than 
ordinary, and for those which require a greater tensile strength such as 
levers, connecting rods and gears the carbon may be raised to from 0.35 to 
0.40 per cent, and in cases where the castings are liable to "pull" on ac- 
count of differences in section, great length, etc., the carbon may be raised 
to 0.50 per cent, silicon 0.30 per cent, and manganese up to 1.10 per cent. 
The castings last referred to will have to be annealed in all cases. 

For the purpose of recarburizing to these points the common materials 
used are ferro-silicon containing about 12 per cent of silicon, silicon-spiegel 
containing about 10 per cent silicon and 20 per cent manganese, and ferro- 
manganese containing 80 per cent manganese. The amount to be used can 
easily be figured by an ec^uation such as was used for calculating cupola 
charges, but it must be borne in mind that an excess of from 20 to 30 per 
cent of ferro-manganese must be used to compensate for that which goes 
to deoxidize the metal, and an excess of about 5 per cent of the calculated 
amount of ferro-silicon. 

The action of the steel in the ladles is somewhat of an indication of 
its carbon content to the close observer. The softer and purer the steel 
the higher is the melting point and therefore in order to have it to remain 

27 



Hozv to Make Converter Steel Castings 



fluid in the ladle and allow it to free itself from gases, it needs to be super- 
heated to a higher degree than the harder grades. It is more difficult to 
"dead melt" soft steel than hard steel, and soft castings are more difficult 
to run and are more liable to blow-holes. This is borne out by the fact 
that gray iron remains fluid in the ladle at a temperature where steel would 
set. 

For making the special or alloy steels such as tungsten steel, chrome 
steel, manganese steel or nickel steel, either the ferro-alloys of these ele- 
ments or the pure products of the electric furnace or alumino-thermic proc- 
ess are used, and the amounts vary widely according to the purpose for 
which the castings are to be used. The materials produced by the alumino- 
thermic process are very useful on account of their concentration, rendering 
it necessary to use only the minimum amount to produce the maximum 
effect, and by the freedom from carbon, etc.. making control of the ultimate 
analysis more simple and certain. 



28 




CHAPTER V 

Hot Cracks in Steel Castings and How They May Be Overcome 



N attempt will be made in this chapter to outline the principal causes 
of one of the greatest difficulties that a steel founder has to contend 
with, and to suggest some means by which it may be overcome, at 
least partially. Cracks in steel castings are of two kinds, which 
differ in their appearance and cause very materially. Hot cracks , take 
place at the time of solidification of the metal or very soon after; cold 
cracks are formed while the metal is below red heat. The former take the 
appearance of a tear, are very ragged and there is a sinking of the metal 
at the edges ; they are generally quite wide and have a film of blue or 
black oxide on their fractured surfaces. Cold cracks, while they may be 
open occasionally, are generally very fine, clean cut as with a knife, and 
unless the castings are carefully inspected may sometimes escape observa- 
tion. Ringing the castings with a hammer will often reveal the presence of 
cold cracks which are almost invisible. It is with the former, or hot cracks, 
that this chapter is intended to deal. 

The two principal causes of hot cracks are obstructions to the free 
contraction of the metal, and unsuitable composition of the metal itself. 
First then look into the causes which may prevent the unrestricted contrac- 
tion of the metal. They are chiefly the rigidity of the mold and the varying 
thicknesses of section of the casting. The mold has to be made sufficiently 
strong to stand the weight of the steel and the fluid pressure of the head 
of metal while it is being poured. Molds for steel castings are generally 
made in dry sand, which consists of silica sand mixed with a certain pro- 
portion of clay to bind it together. And though it is very weak in its green 
or damp condition, it becomes quite hard and firm after baking. The molds 
are faced with a wash made of silica flour and molasses water, which gives 
a very hard, refractory skin. It is therefore important that while the mold 
should be strong' enough to stand all the pressure it is to receive, it should 
not be any stronger than is necessary for the above purpose. Means may 
be provided for making the mold stronger in some parts than others, for 
instance near the gate, where the cutting action is greatest. At these 
places the mold may be made of a stronger grade of sand, or if its shape 
allows, hard cores, or fire brick cvit to shape, may be fitted in, to take the 
wear of the stream of metal. All scpiare corners, both inside and outside, 

29 



How to Make Converter Steel Castings 



should be amply filleted, and wherever a rib or a projectiiii^ arm of the 
pattern protrudes, the sand in its immediate vicinity should be loosened up 
by rammin_^ in cinders, sharp sand or saw dust ; or the mold can be cut 
away to within 2 or 3 inches of the pattern, after it has been dried, and 
the space filled in with burnt sand. 

Another point to be attended to with the idea of reducing^ the danger 
of hot cracks is the drying of the molds. To produce the best results, a 
mold should be rather over-dried than under-dried, that is to say it should 
be almost but not quite burned. A mold that is only just dry is in the 
most rigid possible condition ; it can be baked a good deal more and yet 
preserve sufficient strength to stand the wear and tear of pouring, and it 
will then ofifer much less resistance to the shrinkage of the metal. The 
ideal mold, as has been said before, consists of a hard refractory skin and 
a collapsible backing, which will give way as soon as the cooling skin of 
the casting has become sufticiently rigid to support itself, and begins to 
shrink. It is to the production of these conditions, as nearly as may be 
possible in practice, that foundrymen have to bend their efforts. 



Cores for Steel Castings. 

Defective construction of cores is another fruitful source of cracked 
castings. Coremaking is a branch of the steel foundry trade that does not 
receive the attention it merits. It is equally as important as the mold 
itself, calls for as much skill, and contributes equally to the success or 
failure. And yet we often find the coremaking relegated to a sec- 
ondary place. Core sand mixtures should be as carefully studied as mold- 
ing sand mixtures, and a great saving may be effected, not only in the mat- 
ter of cracking, but in the cost of cleaning and the soundness of the castings 
by careful attention to this point. The same description applies to a core 
as to a mold — it should have a hard, smooth face, which will resist the 
cutting and fusing action of the metal, but it should crumble and fall out 
in the form of powder when burnt. Careful handling will permit the use 
of cores which seemingly are exceedingly delicate. As the author has 
previously stated, cores can be made of almost anything, provided the wash 
is satisfactory. When the core is rammed up it should have a good coat of 
a wash made of silica flour, Ceylon graphite and molasses water, and then 
put in the oven and baked until after scratching the skin the inside is 
thoroughly "rotten". Then another coat of wash or two if necessary may 
be given, and the core is redried. It is surprising how strong this skin 
becomes, and it is no more than 1/32 inch thick. 

In a great many cases a core has to stand much greater pressure than 
the mold itself, as for instance in a pipe or cylinder, where the metal is 
shrinking on the core from every direction. If the core is not collapsible 

30 



How to Make Converter Steel Castiii</,s 



one or two tilings nmst liappen — eitlier it will crack the casting or the core 
will become so hard that its removal will be a very expensive and lengthy 
operation. 

The second jioint. namely the composition of the metal itself, is equally 
important with the foregoing. Any conditions which tend to hot-shortness 
of the metal, whicli means brittleness above red heat, must be carefully 
avoided. The two principal elements found in common practice which 
have this tendency are sulphur and copper, and while their influence is not 
very great in the cold state of the steel, as the metal has to pass 
through the hot short period before cooling to the ordinary temperatures, 
it is important they should be kept as low as possible. Either, by itself, 
is dangerous, but the combination of the two is fatal. As a large pro- 
portion of Eastern iron is made from ores from the Cornwall district, a 
great deal of the scrap available, as well as the iron, has an appreciable 
content of copper, and it is therefore necessary to watch the sulphur most 
carefully, and care should be taken not to allow it to run over 0.045 per 
cent. This is done by selecting melting stock as low as possible in sulphur 
and running a high manganese, which will prevent increase of sulphur 
from the coke, etc., and tend to reduce it, if anything, by the formation 
of sulphide of manganese. 



31 



CHAPTER \'I 

The Steel Foundry Laboratory — Its Equipment and 
THE Necessary Determinations 

ONE of the essentials to success in the operation of a steel foundry is 
a well-equipped laboratory, where the analyses of all the raw ma- 
terials entering into the manufacture, and also that of the finished 
product for checking purposes, can be made. Nowadays, when 
buying pig iron, coke, etc., it is customary to specify the analysis wanted, 
and most producers are willing to guarantee their materials within certain 
limits, supplying with each carload an analysis of that particular lot. At 
all events, it is supposed to be the analysis of that particular carload, but is 
more often the analysis of the cast or pile from which the car was loaded. 
As any cast of pig iron necessarily varies from one end to the other, it is 
wise to take a sample from each car and check the composition before 
using, to avoid mistakes. 

Steel is manufactured today on such close specifications and is re- 
quired to be of such high quality, that it is impossible to get along without 
a laboratory, and the chemist is often the means of saving money to his 
employer by not only avoiding mistakes, but by locating trouble when it 
occurs without loss of time. The laboratory should be located where a 
north light is available and in some part of the works where the vibration 
caused by operation of heavy machinery, cranes, steam hammers, etc., will 
be felt as little as possible, for a great deal of the usefulness of the labora- 
tory consists in the weighing of materials with exceeding accuracy, and 
the balance used is sensitive to the last degree. There should be two rooms, 
one not less than 18 feet square, and the other may be smaller, for the 
balance and the chemist's office. Around three sides of the larger room 
should run benches about 20 inches wide and the other side is left for the 
draught closet, mufifle furnace and sink. The laboratory proper should be 
sheathed entirely in wood, as plaster is affected by the fumes and will 
fall into beakers, etc., with the result of spoiling estimations. There 
should, if possible, be a passage between the two rooms in order that 
through the protection of two doors, the balance may be preserved from 
the action of acid fumes. Under the benches should be drawers for 
apparatus that is not in constant use, filter papers, etc., and these drawers 
should be well fitted to exclude dust. It is very important that exreme 
cleanliness should be observed in all directions. The bench or table sup- 

32 



How to Make Converter Steel Castings 



porting the balance sliould be very heavy and rigid, to minimize vibrations, 
as it is entirely impossible to weigh quickly or accurately on a balance that 
is not perfectly steady. An extra case of wood should be placed over the 
balance to further exclude dust. 

Around the walls of the laboratory should be shelves at a convenient 
height above the benches, to hold the bottles containing re-agents for im- 




Air 




A Handy Still 



Foam 

Filter Pump 



mediate use, and underneath the benches the large Winchester bottles of 
acids may conveniently be stored. 

Apparatus Required for Making Analyses. 

The following is a description of the principal apparatus needed for 
analyses of iron and steel materials, coke, sand, firebrick, etc.. and while 



33 



How to Make Coni'cricr Steel Castings 



more may be provided, or special apparatus used in some cases, the ordi- 
nary work of a steel works laboratory may be done with what is appended 
below : 

The balance should be of the best quality, as it lasts practically for- 
ever and is responsible for the accuracy of results. It should have a short 
beam, not over 7 inches long, wdiich should be of non-corrosive material, 
the longer beam balances make the time of weighing very much longer as 
they take so long to oscillate. A 7-inch beam will be sensitive to 1/10 
milligram, which is sutiicient for all practical purposes. All knife edges 
and planes should be of agate as the steel knife edges will rust in spite of 
all care that may be taken to prevent it. In the balance cases should be 
one or more small vessels containing strong sulphuric acid or chloride of 




Short Beam Balance 



Draught Closet ok Hood 



lime to absorb the moisture in the balance case, and these should be changed 
from time to time. A small camel's hair brush should be used daily to dust 
off the balance. A set of weights is needed running from 50 grams to one 
milligram, and riders to hang on the graduated beam of the balance for 
subdivisions of 1 milligram. The pans of the balance should be large so 
as to accommodate small pieces of apparatus that may have to be weighed 
from time to time, but the metal pans should never be used for the actual 
weighing of materials, instead a small aluminvmi pan, counterpoised by a 
small weight should l)e used. It cannot be too strongly impressed that the 
balance mu.st be .scrupulously clean and in good condition, as this is where 
all accuracy will be destroyed at the outset. 



11 01V to Make Coivz'crtcr Steel (.'astim/s 



Some form of a still is necessary, as pure water must be used in all 
determinations. There are many forms of stills, and a simple and effective 
one may be made by connecting a live steam pipe, if a steam line is handy, 
to a coil which can be kept cold by a stream of water from the laboratory 
service pipe. This is the cheapest way of obtaining a copious supply of 
pure water. If a steam pipe is not available, a self contained sun must 
be provided, and one having a capacity of 20 or 25 gallons per day will be 
large enough. 

For the heavy or gelatinous precipitates, it is necessary to have a filter 
pump to reduce the time of filtering. This consists simply of a specially 
shaped pil'e, having a side inlet, attached to the water supply, and the water 
passing through the vertical pipe causes a powerful suction through the 
side pipe. This is connected to a filter flask, which is a conical flask having 
a side tube and a rubber cork fitted with a glass filter funnel. When filter- 
ing bv means of the pump, it is well to introduce a platinum cone perforated 
with small holes, to prevent the suction from bursting the filter paper. 

The muffle furnace is for incinerating precipitates, fusing refractory 
material, etc., and should be large enough to contain a muffle about 8 x 5^ 
inches. It is heated by a row of five or six bunsen burners in a battery,, 




Hot Plate 

wdiich may be controlled independently, so as to heat different parts of the 
furnace to different temperatures if desired. 

The draught closet is an enclosure containing an iron plate with 
burners beneath, and is used for evaporations, solutions, and for the mak- 
ing of any reactions which give off fumes or gases, which would be un- 
pleasant or dangerous. It should have a chimney with a good draught 
which may be increased by the introduction of a jet of compressed air 
blowing up the chimney. Practically all boiling of liquids is done in this 
closet although there are gas connections at intervals all around the benches. 
The laboratory is in this way kept cooler and more pleasant to work in. 
The plate should not be less than 24 inches long and 16 inches wide, as at 
times a great many beakers will be evaporating at the same time. The 
glass door slides in grooves and is counterljalanced by sash weights. The 
inside of the draught closet is preferably lined with tile. 

The carbon bath is a piece of ajjparatus used for the determination 
of carbon by the color method and consists of a copper vessel about 7 
inches in diameter and 7 inches high. It contains a support for the test 
tubes to be heated, in the form of two perforated discs held together with 

35 



Hoiv to Make Cojivcrtcr Steel Castings 



a wire support. The test tubes are introduced into the holes and are by 
this means held in a vertical ])osition while boilino^, and prevented from 
bein^ broken by the agitation of the water. 

The remainder of the apparatus necessary, probably needs no special 
description and will Ije merely enumerated as follows : 



One air oven, 8x8x8 inches. 

One water bath, copper, with rings. 

One rough weighing balance, and weights, 10 grams to 500 grams. 

One test tube stand. 

Four bunsen burners. 

Two burette stands with clamps 

One burette stand with rings. 

Six iron tripods, 8 inches high. 

One wooden test tube holder. 

One iron mortar and pestle. 

One earthenware mortar and pestle. 

Two pair crucible tongs. 

One platinum crucible, 1 ounce capacity. 

One dozen porcelain crucibles, '/^ ounce capacity. 

One 6-inch horseshoe magnet. 

Six thistle funnel tubes, 12 inches long. 

Six bulb tubes, 6 inches, fitted with two-hole rubber stoppers. 

Two 24-ounce flasks, fitted with two-hole rubber stoppers. 

One acid dropping bottle. 

One dozen 12-ounce beakers, best Bohemian glass. 

One dozen 10-ounce beakers, best Bohemian glass. 

One dozen 5-ounce beakers, best Bohemian glass. 

Four 40-ounce beakers, best Bohemian glass. 

One 100-ounce beaker, best Bohemian glass. 

Four 16-ounce conical flasks. 

Four 8-ounce conical flasks. 

Six 40-ounce conical flasks. 

Six 3-inch ribbed glass funnels. 

One 6-inch glass funnel. 

One 1,000 cubic centimeter graduated flask. 

One 500 cubic centimeter graduated flask. 

One 250 cubic centimeter graduated flask. 

One dessicator. 

One 100 cubic centimeter measuring glass. 

One 25 cubic centimeter pleasuring glass. 

Two dozen test tubes, 8 x 1 inches. 

Six dozen test tubes, 5^ x 6 inches. 

36 



How to Make Converter Steel Castings 



Six 4-inch watcii glasses for beaker covers. 

Six 3-inch watch glasses. 

Six 2-inch watch glasses. 

One thermometer, up to 30O degrees Centigrade. 

One hydrometer, 1,000 to 2,000 specitic gravity. 

Two burettes, 50 cubic centimeter capacity. 

Two burettes, 25 cubic centimeter capacity. 

One pipette, 100 cubic centimeter capacity. 

One pipette, 50 cubic centimeter capacity. 

One pipette, 25 cubic centimeter capacity. 

One pipette, 10 cubic centimeter capacity. 

One pipette, 5 cubic centimeter capacity. 

Two wooden filter stands. 

Six porcelain dishes, 6 inches diameter. 

Six porcelain dishes, 3 inches diameter. 

One platinum dish, 3 inches diameter. 

The above list is not intended to include everything that may be con- 
veniently provided, but it is sufficient for a laboratory employing one chemist 
and by its means he can make all the determinations he will ordinarily be 
called on to make. These are : 

Carbon, by color method. 

Graphitic carbon. 

Manganese by color or gravimetric method in pig iron or steel, volu- 
metric method in ferro-manganese, etc. 

Silicon. 

Sulphur. 

Phosphorus. 

Complete analyses of coke, limestone, sand, firebrick and clay. 

The list of chemicals and re-agents necessary for the above determina- 
tions is not large, while they vary considerably according to the methods of 
estimation used. It is understood that all chemicals used for quantitative 
work must be chemically pure. 



37 



INDEX 

Page 

Alloy Steel 28 

Analysis of Converter Castings 27 

Arithmetical Calculation of Cupola Charge 19 

Arrangement of Converter and Cupola 3 



Blast Box of the Converter 5 

Blower for the Converter 6 

Blower for the Cupola 10 

Blowing: the Steel 25 



Calculating the Cupola Charge 18 

Carbon 27 

Carbon Bath 35 

Charges for the Cupola 18 

Cold Cracks in Steel Castings 29 

Construction of the Converter 4 

Converter in Operation 5 

Converter Lining, Life of 16 

Converter Manhole 16 

Converter Operating Station 6 

Cores for Steel Castings 30 

Core Wasli 30 

Cupola 7 

Cupola Charges 18 

Cupola Charging Floor 9 

Curves of Elimination of Elements in a Typical Blow 24 



Description of a Converter Steel Casting Plant 2 

Difficulties in Blowing Steel — How They May be Overcome . 26 

Draught Closet 35 

Drying the Molds 30 

38 



Index 



EquipniciU uf a Slccl Fuundry 2 

Ferro-]\Ianganese 27 

Ferro-Silicon 27 

Field of tlie Small Converter 1 

Filter Pump 35 

Flux Used in the Cupola 18 

Graphic Method of Calculating- Mixtures 21 

Heating the Converter 22 

Heating the Foundry 2 

Heating the Ladles 11 

Hot Cracks in Steel Castings 29 

Indicator 22 

Iron, Analysis of, for Conversion into Steel 18 

Laboratory Apparatus 33 

Laboratory Balance 34 

Laboratory for the Steel Foundry 32 

Laboratory Still 35 

Ladles 10 

Lining, Converter, Life of 16 

Lining, Converter, Necessary Repairs for 17 

Lining of the Converter 12 

Manganese. Alethod of Calculating 21 

Manhole 16 

Melting Ratio in the Cupola 22 

Molds for Steel Castings 29 

Muffle Furnace 35 

Pouring the Metal into the Converter 4 

Pouring the Metal into the Converter 23 

Recarl)urization of the Metal 26 

Renewal of Tuyeres 17 

Repairing Converter Lining 17 

39 



Index 



Sand Grinder 1 1 

Scrap, Use of, in Cupola Mixtures 18 

Silica Brick for Lining the Converter 13 

Silicon, :\lethod of Calculating 21 

Silicon-Spiegel 27 

Skimming the Iron 22 



Tilting the Converter 6 

Tuyere Block 15 

Tuyeres, Combustion 16 

Tuyeres, Renewal of 17 

Tuyeres, Setting in the Lining 15 

Wooden Forms for Lining the Converter 14 



40 



List of Illustrations 



LIST OF ILLUSTRATIONS. 

Page 

Arrangement of Steel Converter and Cupola 3 

Pouring the Metal Into the Converter 4 

The Converter in Operation 5 

Converter Tilted to Empty the Slag After the Metal Has Been Poured 

Out 7 

The Converter Operating Station 7 

Vertical and Horizontal Sections of Converter 8 

Special Cupola for Melting Iron for the Converter 8 

Heating a Large Ladle With an Oil Burner 9 

Method of Heating Hand Ladles 9 

Oil Burner for Heating Ladles 10 

Roller Type Grinder for Grinding and Mixing Molding Sand 10 

Another Type of Sand Grinder 10 

Wood Form Used for Lining the Converter 13 

One of the Wood Forms Set in the Converter 14 

Tuyere Block 15 

(iraphic Method of Figuring Cupola Charges 20 

Indicator for Noting Position of the Converter 23 

Curves of Elimination of Elements in a Typical Blow 24 

A Handy Laboratory Still 33 

Filter Pump 33 

Short Beam Balance 34 

Draught Closet or Hood 34 

Hot Plate 35 



41 



36 91 



